Tool assembly with replaceable cartridge assembly

ABSTRACT

A surgical stapling device includes a tool assembly that includes an anvil assembly and a cartridge assembly. The cartridge assembly includes a channel member that includes structure for releasably engaging the anvil assembly to allow for separation of the entire cartridge assembly from the anvil assembly after each use of the stapling device.

FIELD

This technology is generally related to surgical stapling devices, and more particularly, to surgical stapling devices including replaceable cartridge assemblies.

BACKGROUND

Surgical stapling devices for endoscopic use are well known and commonly used to minimize patient trauma and reduce patient recovery times. Typically, endoscopic stapling devices include a tool assembly that has an anvil assembly and a cartridge assembly that are coupled to each other by a pivot member and movable in relation to each other between open and clamped positions. The cartridge assembly includes a staple cartridge that supports a plurality of staples. In order to facilitate reuse of the surgical stapling device and reduce costs associated with a surgical procedure, it is known to include the tool assembly as part of a replaceable reload assembly that can be replaced after each firing of the surgical stapling device. It is also known to include a replaceable staple cartridge on the cartridge assembly that can be replaced to facilitate reuse of the surgical stapling device.

The reload assembly includes the tool assembly and a proximal body portion that supports a drive assembly for actuating the tool assembly. Replacement of the entire reload assembly after each firing of the surgical stapling device can be costly. The staple cartridge typically includes a cartridge body that supports a plurality of surgical staples. The cartridge body is flimsy and sometimes difficult to handle.

A continuing need exists for an inexpensive, more robust cartridge assembly that can be easily replaced to facilitate reuse of the surgical stapling device.

SUMMARY

One aspect of this disclosure is directed to a tool assembly including an anvil assembly, a cartridge assembly, and retention structure. The anvil assembly includes an anvil body and a mounting member. The anvil body defines a longitudinal axis and includes a staple forming surface, a proximal portion, and a distal portion. The proximal portion of the anvil body has spaced flange portions positioned on opposite sides of the staple forming surface. The anvil assembly defines insertion slots on each side of the anvil assembly that extend along axes that define an acute angle Ω with the longitudinal axis of the anvil body. The cartridge assembly includes a cartridge body and a channel member. The cartridge body defines a central knife slot and a plurality of staple pockets positioned on each side of the central knife slot. The channel member includes a base member and spaced side walls that define a channel that receives the cartridge body. Each of the side walls has a proximal portion that supports a protrusion that is received within one of the insertion slots of the anvil body to pivotably couple the anvil assembly to the cartridge assembly. The retention structure is supported on the tool assembly to retain the protrusions within the insertion slots.

Other aspects of the disclosure are directed to a surgical stapling device including a handle assembly, an adapter assembly supported on the handle assembly, and a tool assembly. The tool assembly is supported on the adapter assembly and includes an anvil assembly, a cartridge assembly, and retention structure. The anvil assembly includes an anvil body and a mounting member. The anvil body defines a longitudinal axis and includes a staple forming surface. The anvil body has a proximal portion and a distal portion. The proximal portion of the anvil body has spaced flange portions positioned on opposite sides of the staple forming surface. The anvil assembly defines insertion slots on each side of the anvil assembly. The insertion slots extend along axes that define an acute angle Ω with the longitudinal axis of the anvil body. The cartridge assembly includes a cartridge body and a channel member. The cartridge body defines a central knife slot and a plurality of staple pockets positioned on each side of the central knife slot. The cartridge channel includes a base member and spaced side walls that define a channel that receives the cartridge body. Each of the side walls of the channel member has a proximal portion that supports a protrusion that is received within one of the insertion slots of the anvil body to pivotably couple the anvil assembly to the cartridge assembly. The retention structure is supported on the tool assembly to retain the protrusions within the insertion slots.

In aspects of the disclosure, each of the insertion slots includes an inlet portion and a base portion that has widened portions which allow the protrusions to rotate within the insertion slots.

In some aspects of the disclosure, the angle Ω is from about 15 degrees to about 35 degrees.

In certain aspects of the disclosure, the angle Ω is about 25 degrees.

In aspects of the disclosure, the insertion slots are formed in the spaced flange portions of the anvil body.

In some aspects of the disclosure, the insertion slots are formed in opposite sides of the mounting member.

In certain aspects of the disclosure, the retention structure includes detents formed on the anvil body and openings formed in the channel member. The detents are positioned to be received within the openings as the anvil assembly is pivoted towards the cartridge assembly with the protrusions received in the insertion slots.

In aspects of the disclosure, a drive assembly includes a clamping member having a first beam positioned to engage the cartridge assembly, a second beam positioned to engage the anvil assembly, and a vertical strut connecting the first beam to the second beam.

In some aspects of the disclosure, the retention structure includes a biasing member positioned to urge the clamp member into engagement with the channel member of the cartridge assembly.

Other aspects of the disclosure are directed to a tool assembly including a cartridge assembly, an anvil assembly, and a drive assembly. The anvil assembly includes an anvil body having a proximal portion and a mounting member. The mounting member is fixedly supported on the proximal portion of the anvil body and defines a longitudinal channel and a transverse through bore that intersects the longitudinal channel. The mounting member further including two balls received within the through bore. The cartridge assembly includes a cartridge body and a channel member. The cartridge body defines a central knife slot and a plurality of staple pockets positioned on each side of the central knife slot. The channel member includes a base member and spaced side walls that define a channel that receives the cartridge body. Each of the side walls has a proximal portion that defines a circular bore. The drive assembly includes a clamp member that has a first beam positioned to engage the cartridge assembly, a second beam positioned to engage the anvil assembly, and a vertical strut connecting the first beam to the second beam. The clamp member is received within the longitudinal slot to urge the two balls outwardly of the through bore into the circular bores of the channel member to pivotably secure the cartridge assembly to the anvil assembly.

Other features of the disclosure will be appreciated from the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

Various aspects of the disclosed staple cartridge are described herein below with reference to the drawings, wherein:

FIG. 1 is a side perspective view of a surgical stapling device including a tool assembly with a replaceable cartridge assembly according to aspects of the disclosure;

FIG. 2 is a side perspective exploded view of the cartridge assembly of the surgical stapling device shown in FIG. 1;

FIG. 3 is a perspective view of the anvil assembly of the tool assembly shown in FIG. 2;

FIG. 4 is an enlarged view of the indicated area of detail shown in FIG. 3;

FIG. 5 is an enlarged view of the indicated area of detail shown in FIG. 3;

FIG. 6 is a side perspective view of a reload assembly of the surgical stapling device shown in FIG. 1 with a cartridge assembly of the tool assembly separated from an anvil assembly of the tool assembly;

FIG. 7 is an enlarged view of the indicated area of detail shown in FIG. 6;

FIG. 8 is a side view of the tool assembly shown in FIG. 1 as the cartridge assembly is about to be installed onto the tool assembly;

FIG. 9 is a side view of the tool assembly shown in FIG. 1 in the process of installing the cartridge assembly onto the tool assembly;

FIG. 10 is a side view of the tool assembly shown in FIG. 1 in the process of installing the cartridge assembly onto the tool assembly;

FIG. 11 is an enlarged view of the indicated area of detail shown in FIG. 10;

FIG. 12 is a cross-sectional view taken along section line 13-13 of FIG. 10;

FIG. 13 is an enlarged view of the indicated area of detail shown in FIG. 1;

FIG. 14 is side view of an alternate version of the tool assembly of the surgical stapling device shown in FIG. 1;

FIG. 15 is an enlarged view of the indicated area of detail shown in FIG. 14;

FIG. 16 is a side perspective view of the tool assembly shown in FIG. 14 with the cartridge assembly separated from the reload assembly;

FIG. 17 is side perspective view of another alternate version of the tool assembly of the surgical stapling device shown in FIG. 1;

FIG. 18 is a side cross-sectional view taken along section line 18-18 of FIG. 17 with the cartridge assembly locked onto the reload assembly; and

FIG. 19 is a side cross-sectional view taken along section line 18-18 of FIG. 17 as the cartridge assembly is being locked onto the reload assembly.

DETAILED DESCRIPTION

The disclosed surgical stapling device will now be described in detail with reference to the drawings in which like reference numerals designate identical or corresponding elements in each of the several views. However, it is to be understood that the disclosed embodiments are merely exemplary of the disclosure and may be embodied in various forms. Well-known functions or constructions are not described in detail to avoid obscuring the disclosure in unnecessary detail. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the disclosure in virtually any appropriately detailed structure. In addition, directional terms such as front, rear, upper, lower, top, bottom, distal, proximal, and similar terms are used to assist in understanding the description and are not intended to limit the disclosure. As used herein, the terms “parallel”, “perpendicular”, and “aligned” are understood to include relative configurations that are substantially parallel, substantially perpendicular, and substantially aligned, i.e., up to about + or −10 degrees from true parallel, true perpendicular, true alignment.

The disclosure is directed to a tool assembly including a cartridge assembly and an anvil assembly. The cartridge assembly includes a channel member that includes structure for releasably engaging the anvil assembly to allow for separation of the entire cartridge assembly from the anvil assembly after each use of the stapling device.

FIG. 1 illustrates a surgical stapling device shown generally as stapling device 10 that includes a handle assembly 12, an elongate body or adapter 14, and a tool assembly 16. As illustrated, the handle assembly 12 is powered and includes a stationary handgrip 18 and actuation buttons 20. The actuation buttons 20 are operable to actuate various functions of the tool assembly 16 via the adapter 14, i.e., approximation of the tool assembly and stapling and cutting of tissue. In certain aspects of the disclosure, the handle assembly 16 supports batteries (not shown) that provide power to the handle assembly 12 to operate the stapling device 10. Although the stapling device 10 is illustrated as a powered stapling device, it is envisioned that the advantages of this disclosure are suitable for use with manually powered surgical stapling devices as well as robotically controlled stapling devices. In some aspects of the disclosure, the tool assembly 16 forms part of a reload assembly 22 that is releasably coupled to a distal portion of the adapter 14 and can be replaced to facilitate reuse of the stapling device 10. U.S. Pat. No. 5,865,361 (“'361 patent”) describes a stapling device that describes exemplary aspects of a reload assembly that is releasably coupled to a body portion of the stapling device. Alternately, the tool assembly 16 can be secured directly to the distal portion of the elongate body 14.

The tool assembly 16 of the stapling device 10 includes a cartridge assembly 30 and an anvil assembly 32. Each of the cartridge and anvil assemblies 30 and 32 includes a proximal portion and a distal portion. The cartridge assembly 30 and the anvil assembly 32 are coupled together such that the tool assembly 16 can pivot between an open position (FIG. 1) in which the distal portions of the cartridge and anvil assemblies 30 and 32 are spaced from each other and a clamped position in which the cartridge and anvil assemblies 30 and 32 are in juxtaposed alignment.

FIG. 2 illustrates the cartridge assembly 30 which includes a cartridge body 34, a channel member 36, a staple guard 38, staple pushers 40, an actuation sled 42, and staples 44. The cartridge body 34 has a tissue engaging surface 46 and defines a central knife slot 48 and a plurality of staple pockets 49 positioned on each side of the central knife slot 48. Each of the staple pockets 49 receives a staple 44 and one of the pushers 40. The actuation sled 42 is movable within the cartridge body 34 from a retracted position to an advanced position to drive the pushers 40 upwardly from within the cartridge body 34 towards the tissue engaging surface 46 of the cartridge body 34 to eject the staples 44 from the cartridge body 34. Although the cartridge body 34 is illustrated as being linear, it is envisioned that the cartridge body 34 may have a non-linear configuration along its longitudinal axis. For a detailed description of the operation of an exemplary actuation sled, see, e.g., the '361 patent.

The staple guard 38 is secured to a lower side of the cartridge body 34 opposite to the tissue engaging surface 46 and provides a cover to prevent the pushers 40 and the staples 44 from falling from the lower side of the cartridge body 34. In certain aspects of the disclosure, the guard includes openings 50 that receive projections 52 on the cartridge body 34 such that the guard 38 can be snap-fit onto the cartridge body 34. Each of the projections 62 can include an angled surface 52 a that is angled outwardly towards the tissue engaging surface 46 of the cartridge body 34. The angled surface 52 a allows portions of the guard 38 to be cammed outwardly past the projections 52 as the guard 38 is attached to the cartridge body 32. The guard 38 defines a knife slot 54 that is aligned with the knife slot 48 formed in the cartridge body 42.

The channel member 36 includes a base wall 60 and side walls 62 that define a channel 64. The channel 64 receives the cartridge body 34. The side walls 62 of the channel member 36 define openings 66 that receive the projections 52 of the cartridge body 52 to secure the cartridge body 34 within the channel 64 of the channel member 36. The channel member 36 includes a distal portion 68 and a proximal portion 70. The proximal portion 70 of the channel member 36 supports protrusions 72. In aspects of the disclosure, the protrusions 72 are formed integrally with the side walls 62 of the channel member 36 and extend outwardly from the channel member 36 away from the channel 64 defined by the channel member 36. In some aspects of the disclosure, the protrusions 72 have a rectangular configuration. Alternately, other configurations are envisioned including square, oval and round.

The cartridge assembly 30 includes biasing members 80. In aspects of the disclosure, the biasing members 80 include leaf springs which include securement portions 82 that are received within openings 84 in a proximal portion of the cartridge body 34 to secure the biasing members 80 to the cartridge body 34. The biasing members 80 are positioned in cantilevered fashion to engage the anvil assembly 32 to urge the cartridge and anvil assemblies 30 and 32 towards the open position.

FIGS. 3-7 illustrate the anvil assembly 32 which includes an anvil body 90 and a dissector tip 92. The anvil body 90 defines a longitudinal axis “X” (FIG. 3) and a central knife slot 94 and includes a distal portion 96, a proximal portion 98, and a staple forming surface 100. The staple forming surface 100 includes forming pockets 102 positioned on each side of the central knife slot 94. The forming pockets 102 are aligned with the staple pockets 49 when the tool assembly 16 is in its clamped position. The dissector tip 92 is secured to the distal portion 96 of the anvil body 90 and is configured to separate tissue as the tool assembly 16 (FIG. 1) is advanced to a surgical site during a surgical procedure. It is envisioned that the anvil assembly 32 need not include a dissector tip 92.

The proximal portion of the anvil assembly 32 includes two spaced flange portions 104 that extend downwardly from the staple forming surface 100 towards the cartridge assembly 30 (FIG. 1). Each of the spaced flange portions 104 defines an insertion slot 106 that receives the protrusion 72 on the channel member 36 of the cartridge assembly 30. Each of the insertion slots 106 is defined in a distal portion of one of the spaced flange portions 104 and has an inlet portion 108 (FIG. 5) and a base portion 110. The inlet portion 108 extends along an axis “Y” that defines an acute angle Ω with the longitudinal axis “X” of the anvil body 90. In some aspects of the disclosure, the angle Ω is from about 15 degrees and about 35 degrees, and may be about 25 degrees. The base portion 110 includes widen portions 110 a that allow the protrusion 72 of the channel member 36 to pivot within the insertion slot 106.

Each of the flange portions 104 includes an inner surface 112 that supports a detent 114 (FIG. 4). The detents 114 are positioned on the flange portions 104 at a location distally of the insertion slots 106 and include tapered side walls 114 a. When the protrusions 72 of the channel member 36 are received in the base portions 110 of the insertion slots 106 of the anvil assembly 32, and the cartridge assembly 30 is rotated towards the anvil assembly 32, the detents 114 are received in the proximal-most openings 66 a of the channel member 36 as described in detail below. The tapered surfaces 114 a of the detents 114 allow the detents 114 to pass over the side walls 62 (FIG. 2) of the channel member 36 and snap into the openings 66 a in the channel member 36. The proximal-most openings 66 a and the detents 114 form retention structure to retain the protrusions 72 within the insertion slots 106. The openings 66 a are dimensioned to allow the cartridge assembly 30 to pivot to the clamped position with the detents 114 received within the openings 66 a.

FIGS. 8-13 illustrate the cartridge assembly 30 as the cartridge assembly 30 is coupled to the anvil assembly 32. When the cartridge assembly 30 is coupled to the anvil assembly 32, the protrusion 72 on the channel member 36 is aligned with and moved into the insertion slot 106 in the direction of arrows “A” in FIG. 8 until the protrusion 72 engages the proximal end of the insertion slot 106. When the protrusions 72 of the channel 36 engage the proximal ends of the insertion slots 106 of the anvil assembly 32, the cartridge assembly 30 is rotated in the direction of arrow “B” in FIG. 10 towards the anvil assembly 32 to move the detents 114 of the anvil assembly 32 into the openings 66 a in the channel member 36 of the cartridge assembly 30. When the detents 114 are received within the openings 66 a, the longitudinal axis of the anvil assembly 32 and the longitudinal axis of the cartridge assembly 30 define an acute angle of about 12 degrees. It is envisioned that this angle could be selectively changed to provide a larger or smaller spacing of the distal ends of the cartridge and anvil assemblies 30 and 32 when the tool assembly 16 is in the open position. As described above, as the cartridge assembly 30 approaches the anvil assembly 32, the detents 114 of the anvil assembly 32 engage the side walls 62 of the channel member 36 such that the flange portions 104 flex outwardly to allow the detents 114 to pass over the side walls 62 of the channel member 36 and snap into the openings 66 a of the channel member 36. When the detents 114 of the anvil assembly 32 are received into the openings 66 a of the channel member 36, the protrusions 72 of the channel member 36 are retained in the base portion 110 of the insertion slot 106 of the anvil assembly 32. As described above, the widen portions 110 a of the base portion 110 allow the protrusions 72 of the channel member 36 to pivot within the insertion slots 106 of the anvil assembly 32.

FIGS. 14 and 15 illustrate another version of the tool assembly according to this disclosure shown generally as tool assembly 216. The tool assembly 216 is substantially the same as tool assembly 16 (FIG. 10) described above except that the detents 114 on the flange portions 104 (FIG. 10) of the anvil assembly 32 (which were provided to retain the protrusions 72 within the insertion slot 106) have been replaced by a biasing member 214. The constructions of the cartridge and anvil assemblies 230 and 232 of the tool assembly 216 are identical to that of the tool assembly 16 (FIG. 10) in all other respects.

The tool assembly 216 (as does the tool assembly 16) includes a drive assembly 218 including a clamp member 220 that has a first beam 222, a second beam 224, and a vertical strut 226 that connects the first beam 222 to the second beam 224. The drive assembly 218 is movable from a retracted position to an advanced position to move the clamp member 220 through the tool assembly 216 to pivot the tool assembly 216 from the open position to a clamped position and to subsequently fire staples. As the clamp member 220 moves through the tool assembly 216, the second beam 224 engages a ramp surface 228 (FIG. 15) on the channel member 236 of the cartridge assembly 230. Engagement between the second beam 224 of the clamp member 220 and the ramp surface 228 of the channel member 236 moves the cartridge assembly 230 towards the anvil assembly 232 to move the tool assembly 216 towards the clamped position.

In the tool assembly 216, the biasing member 214 is positioned to bias the clamp member 220 in the direction of arrow “C” in FIG. 15 into engagement with the ramp surface 228 of the channel member 236 of the cartridge assembly 230. In aspects of the disclosure, the biasing member 214 includes a coil spring that is positioned between a proximal surface of the clamp member 220 and a distal surface of a mounting member 250 of the tool assembly 216. The mounting member 250 is fixedly secured to a proximal portion of the anvil assembly 232 and the cartridge assembly 230 is pivotably coupled to the mounting member 250. In use, the biasing member 214 urges the clamp member 220 into engagement with the channel member 236 of the cartridge assembly 230 to pivot the cartridge assembly 230 in the direction of arrow “D” in FIG. 14 towards anvil assembly 232. This engagement retains the protrusions 272 within the base portions 310 of the insertion slots 306. The biasing member 214 forms the retention structure of the tool assembly 216 to retain the protrusions 272 within the base portions 310 of the insertion slots 306.

FIG. 16 illustrates another version of the disclosed tool assembly shown generally as tool assembly 416. The tool assembly 416 is substantially identical to the tool assembly 16 except that the insertion slot 406 is formed in the mounting portion 250 of the tool assembly 416. In tool assembly 416, the protrusions 472 are formed on inner surfaces of the side walls 462 of the channel member 436 of the cartridge assembly 430. The protrusions 472 are received within the insertion slots 406 in the same manner as the protrusions 72 are received within the insertion slots 106. As such, this process will not be described further herein. It is noted that although not shown, the anvil assembly 432 includes detents identical to the detents 114 (FIG. 3) that are received within the openings 466 a of the channel member 436 to retain the protrusions 474 within the insertion slots 406.

FIGS. 17-19 illustrate yet another version of the tool assembly according to this disclosure shown generally as tool assembly 516. The tool assembly 516 includes a cartridge assembly 530, an anvil assembly 532, a mounting member 534, and a drive assembly 536. As described above in regard to tool assembly 216 (FIG. 15), the mounting member 534 is fixedly secured to a proximal portion of the anvil assembly 532 and supports the cartridge assembly 530 for pivoting movement in relation to the anvil assembly 532. The mounting member 534 defines a longitudinal channel 534 a that receives a drive beam 536 a of the drive assembly 536 to facilitate movement of the drive assembly 536 into the tool assembly 516 between its retracted and advanced positions. In addition, the drive assembly 536 is identical to the drive assembly 220 (FIG. 14) described above and includes a clamp member 540 that has a first beam 542, a second beam 544, and a vertical strut 546 that connects the first beam 542 to the second beam 544. As described above in regard to the drive assembly 218, the drive assembly 536 is movable from a retracted position to an advanced position to move the clamp member 540 through the tool assembly 516 to pivot the tool assembly 516 from an open position to a clamped position and to subsequently fire staples.

The cartridge assembly 530 includes a channel member 550 that has side walls 552 and a base wall 554 that define a channel 556 that receives a staple cartridge 558. Each of the side walls 552 of the channel member 550 includes a proximal portion 552 a that defines a circular bore 560. Alternately, the bores 560 need not extend through the side walls 552 of the channel member 550 and may be in the form of a circular recess or bind bore.

The mounting member 534 defines a through bore 562 that receives two spherical members or balls 564. The balls 564 are dimensioned to be contained within the through bore 562 when the clamp member 540 of the drive assembly 536 is positioned proximally of the through bore (FIG. 19). When the clamp member 540 is advanced to a position in which the vertical strut 546 is positioned between the balls 564, the balls 564 are pushed outwardly and project from the through bore 562.

In order to secure the cartridge assembly 530 to the anvil assembly 532, a proximal portion 552 a of the channel member 536 is positioned about the mounting member 534 with the mounting member 534 received within the channel 556 such that the balls 564 are aligned with the bores 560 in the channel member 536. Once the channel member 536 is properly positioned in relation to the mounting member 534, the drive assembly 536 can be advanced to move the vertical strut 546 of the clamp member 540 between the balls 564 to urge the balls 564 outwardly from the through bore 562 into the bores 560 of the channel member 536 to pivotably secure the channel member 536 to the mounting member 534.

Persons skilled in the art will understand that the devices and methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments. It is envisioned that the elements and features illustrated or described in connection with one exemplary embodiment may be combined with the elements and features of another without departing from the scope of the disclosure. As well, one skilled in the art will appreciate further features and advantages of the disclosure based on the above-described embodiments. Accordingly, the disclosure is not to be limited by what has been particularly shown and described, except as indicated by the appended claims. 

What is claimed is:
 1. A tool assembly comprising: an anvil assembly including an anvil body and a mounting member, the anvil body defining a longitudinal axis and including a staple forming surface, the anvil body having a proximal portion and a distal portion, the proximal portion of the anvil body having spaced flange portions positioned on opposite sides of the staple forming surface, the anvil assembly defining insertion slots on each side of the anvil assembly, the insertion slots extending along axes that define an acute angle Ω with the longitudinal axis of the anvil body; a cartridge assembly including a cartridge body and a channel member, the cartridge body defining a central knife slot and a plurality of staple pockets positioned on each side of the central knife slot, the channel member including a base member and spaced side walls that define a channel, the channel receiving the cartridge body, each of the side walls having a proximal portion that supports a protrusion having a rectangular configuration, the protrusions received within the insertion slots of the anvil body to pivotably couple the anvil assembly to the cartridge assembly; and retention structure supported on the tool assembly to retain the protrusions within the insertion slots.
 2. The tool assembly of claim 1, wherein each of the insertion slots includes an inlet portion and a base portion, wherein the base portions include widened portions which allow the protrusions to rotate within the insertion slots.
 3. The tool assembly of claim 2, wherein the angle Ω is from about 15 degrees to about 35 degrees.
 4. The tool assembly of claim 2, wherein the angle Ω is about 25 degrees.
 5. The tool assembly of claim 1, wherein the insertion slots are formed in the spaced flange portions of the anvil body.
 6. The tool assembly of claim 1, wherein the insertion slots are formed in opposite sides of the mounting member.
 7. The tool assembly of claim 1, wherein the retention structure includes detents formed on the anvil body and openings formed in the channel member, the detents positioned to be received within the openings as the anvil assembly is pivoted towards the cartridge assembly with the protrusions received in the insertion slots.
 8. The tool assembly of claim 1, further including a drive assembly including a clamping member, the clamping member including a first beam positioned to engage the cartridge assembly, a second beam positioned to engage the anvil assembly, and a vertical strut connecting the first beam to the second beam.
 9. The tool assembly of claim 8, wherein the retention structure includes a biasing member positioned to urge the clamping member into engagement with the channel member of the cartridge assembly.
 10. A surgical stapling device comprising: a handle assembly; an adapter assembly supported on the handle assembly; and a tool assembly supported on the adapter assembly, the tool assembly including: an anvil assembly including an anvil body and a mounting member, the anvil body defining a longitudinal axis and including a staple forming surface, the anvil body having a proximal portion and a distal portion, the proximal portion of the anvil body having spaced flange portions positioned on opposite sides of the staple forming surface, the anvil assembly defining insertion slots on each side of the anvil assembly, the insertion slots extending along axes that define an acute angle Ω with the longitudinal axis of the anvil body, each of the insertion slots having an inlet portion and a base portion, wherein the inlet portion is positioned distally of the base portion; a cartridge assembly including a cartridge body and a channel member, the cartridge body defining a central knife slot and a plurality of staple pockets positioned on each side of the central knife slot, the channel member including a base member and spaced side walls that define a channel, the channel receiving the cartridge body, each of the side walls having a proximal portion that supports a protrusion having a rectangular configuration, the protrusions received within the insertion slots of the anvil body through the inlet portion of the insertion slots to pivotably couple the anvil assembly to the cartridge assembly; and retention structure supported on the tool assembly to retain the protrusions within the insertion slots.
 11. The surgical stapling device of claim 10, wherein the base portions of the insertion slots include widened portions which allow the protrusions to rotate within the insertion slots.
 12. The of surgical stapling device claim 11, wherein the angle Ω is from about 15 degrees to about 35 degrees.
 13. The surgical stapling device of claim 11 wherein the angle Ω is about 25 degrees.
 14. The surgical stapling device of claim 10, wherein the insertion slots are formed in the spaced flange portions of the anvil body.
 15. The surgical stapling device of claim 10, wherein the insertion slots are formed in opposite sides of the mounting member.
 16. The surgical stapling device of claim 10, wherein the retention structure includes detents formed on the anvil body and openings formed in the channel member, the detents positioned to be received within the openings as the anvil assembly is pivoted towards the cartridge assembly with the protrusions received in the insertion slots.
 17. The surgical stapling device of claim 10, further including a drive assembly including a clamping member, the clamping member including a first beam positioned to engage the cartridge assembly, a second beam positioned to engage the anvil assembly, and a vertical strut connecting the first beam to the second beam.
 18. The surgical stapling device of claim 17, wherein the retention structure includes a biasing member positioned to urge the clamping member into engagement with the channel member of the cartridge assembly. 